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MDEV-10341: InnoDB: Failing assertion: mutex_own(mutex) - mutex_exit_func

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Followup from 5.5 patch. Removing memory barriers on intel is wrong as
this doesn't prevent the compiler and/or processor from reorganizing reads
before the mutex release. Forcing a memory barrier before reading the waiters will
guarantee that no speculative reading takes place.
This commit is contained in:
Vicențiu Ciorbaru 2016-08-18 14:00:40 +03:00
parent 4eb898bb16
commit ed99e2cdd3
2 changed files with 2 additions and 18 deletions
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10
storage/innobase/include/os0sync.h
View File

@ -849,15 +849,7 @@ for synchronization */
} while (0);
/** barrier definitions for memory ordering */
#ifdef IB_STRONG_MEMORY_MODEL
/* Performance regression was observed at some conditions for Intel
architecture. Disable memory barrier for Intel architecture for now. */
# define os_rmb do { } while(0)
# define os_wmb do { } while(0)
# define os_mb do { } while(0)
# define IB_MEMORY_BARRIER_STARTUP_MSG \
"Memory barrier is not used"
#elif defined(HAVE_IB_GCC_ATOMIC_THREAD_FENCE)
#if defined(HAVE_IB_GCC_ATOMIC_THREAD_FENCE)
# define HAVE_MEMORY_BARRIER
# define os_rmb __atomic_thread_fence(__ATOMIC_ACQUIRE)
# define os_wmb __atomic_thread_fence(__ATOMIC_RELEASE)

10
storage/xtradb/include/os0sync.h
View File

@ -900,15 +900,7 @@ for synchronization */
} while (0);
/** barrier definitions for memory ordering */
#ifdef IB_STRONG_MEMORY_MODEL
/* Performance regression was observed at some conditions for Intel
architecture. Disable memory barrier for Intel architecture for now. */
# define os_rmb do { } while(0)
# define os_wmb do { } while(0)
# define os_mb do { } while(0)
# define IB_MEMORY_BARRIER_STARTUP_MSG \
"Memory barrier is not used"
#elif defined(HAVE_IB_GCC_ATOMIC_THREAD_FENCE)
#if defined(HAVE_IB_GCC_ATOMIC_THREAD_FENCE)
# define HAVE_MEMORY_BARRIER
# define os_rmb __atomic_thread_fence(__ATOMIC_ACQUIRE)
# define os_wmb __atomic_thread_fence(__ATOMIC_RELEASE)